Following the example set by Raph with his royalty free license
for using his patents in
free software (released under the GPL), there is now a
similar license
granted by Ericsson for some proposed improvements of the
TCP protocol (the Eifel algorithm). More power to free
software!

That license
allows GPLed software to include the proposed improvements
to the TCP stack, as well as any operating system that is
entirely Open Source. So this covers Linux, FreeBSD,
OpenBSD and NetBSD, among others.

(Disclaimer: I work for Ericsson and I contributed to the
wording of that license, but I am currently only speaking
for myself, not for my employer.)